Particle mill system



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Oct. 20, 1959 Filed June 7, 1954 G. M. CROFT PARTICLE MILL SYSTEM 4 Sheets-Sheet 1 Q) m m 'n '8 m Q INVENTOR GEORGE M CROFT I Fig.5.

Oct. 20, 1959 Filed June 7, 1954 G. M. CROFT PARTICLE MILL SYSTEM 4 Sheets-Sheet 2 INVENTOR GEORGE M. CROFT Oct. 20, 1959 s. M. CROFT PARTICLE mu. SYSTEM 4 Sheets-Sheet 3 Filed Jun '7, 1954 r M R R I. Y m y v .w. M a N E 4% 6 r R L 0 4 E 2 6 a 4? 2 n 7 Ma 2 6 L w W 2 M p 1 a I. a 2 r 4 3 OJ 5 m 3 5 =6 o x H... 1 0 7 5 I \4 J 1 u d fi I wa HHHHEL I- ficv x h "a w v F m fi 5 4 L. F 5 5 2 0a B w 4 Sheets-Sheet 4 Filed June '7, 1954 INVENTOR GEORGE M. CROFT of Figure 2;

Figure 6 is a detailed view in section taken along line United States Patent PARTICLE MILL SYSTEM George M. Croft, Fox Chapel Borough, Pa., 'assignor to Majac, Inc., Sharpsburg, Pa., a corporation of Pennsylvania. 7

Application June 7, 1954, Serial No. 434,947

- 11 Claims. Cl. 241-39 This invention relates to a particle mill system 'for parting and classifying solid particles utilizing jet circulating means. More particularly, this invention pertains to impact reduction in combination with classification of desired material and removal of undesired material from the new system.

In the exfoliation and/ or grinding of mica, for example, prior pulverizing mills of the impact jet pulverizer kind utilizing a gaseous circulating medium, such as air or steam, have been considered unsuitable as a practical matter. Moreover, the entire feed to such prior mills was operated upon until pulverized to an extent which satisfied the classification operation accompanying such prior mills.

On the other hand, in the instant invention, a new particle system is provided in which a raw material like mica is readily separated from its matrix material which may be schist and is reduced in size and the cleavage of mica particles from one another is achieved to the desired extent in terms of capacity and of quality. In addition, foreign material such as the heavy rockmatrix itself is collected and removed entirely from my new system. At the same time, uniformity of operation and continuity of classification is carried on in a new Way to achieve an end product with circulation and recirculation of the desired material until it conforms to the predetermined specification.

Other objects and advantages will be apparent from the following description and the accompanying drawings, which are illustrative only, in which Figure 1 is a side view in elevation of one embodiment of my new device; 1

Figure 2 is an end view in elevation of the embodiment shown in Figure l;

Figure 3 is a side view partly in section taken along line IIIIII of Figure 2; j

Figure 4 is a View in section taken along line IV-IV of Figure 2; V 1

Figure 5 is a view in section taken along line V-V VIVI of Figure 2;

Figure 7 is a partial view in section taken along line VII-VII of Figure l; and

Figure 8 is a detailed view partly in section of a discharge box assembly for a heavy material removal device.

Referring to the drawings, a newparticle mill made in accordance with my invention may comprise a base 10 on which various parts of the new device are supported. Thus, a wholly enclosed cubical impact chamber 11 is provided and lined with wear plates 12. A pair of housings 13 for jets 14 are connected to chamber 11 and surround openings 15 through the side walls of chamber 11 in directly opposed relation. Each jet 14 may comprise a nozzle 16 and an axially spaced barrel 17. The discharge ends of the respective barrels 17 extend through the openings 15 and are properly supported therein for adjustable axial movement, as desired, to

provide the selected distance between the inner discharge ends of the-respective barrels 17. A gas'eousfluid like compressed air enters the outer end 18 of each nozzle 16 and supplies a circulating medium for the new mill in operation. Entry chambers 19 in the form of funnels deposit material passing thereinto from above in position to be aspirated into the inlet end 20 of the barrel 17 by virtue of the force of gravity, the circulating gaseous medium and the force of the discharge from each nozzle 16. The entire mill is properly bushed and gasketed and may be suitably lagged where such is desired so that the operation is wholly enclosed.

A raw material feed device 21 is provided with a hopper 22 and a foundation member 23. Hopper 22 may be provided with a rotating shaft 24 having beater spokes 25 thereon to keep raw material deposited in the top.

' of hopper 22 from unduly lumping. The bottom of hopper '22 is open and empties into the interior of av conveyor tube 26 in which an endless screw 27 rotates to feed such raw material through the wall of chamber 11 and out of discharge end 28 of tube 26. Shaft 24 and the shaft of screw 27 are provided with sprockets such shafts. One side of chamber 11 may be made in the form ofa removable door 30.

In operation, the impact of solids Within chamber 11 occasioned by the oppositely directed discharge from the jets 14 and the forces present carry all material,

gaseous and solid including raw material discharged from end 28 of tube 26, into two riser pipes 31 which take the total contents of impact chamber 11 out of openings 32 and discharge such contents through open-.

imposed above impact chamber 11 and capable of being supported in that superposed relation by riser pipes 31, byreturn pipes 36 and by downcomer pipes 37. Wall 38 of primary classifier 34 is surrounded by a ring chamber 39 adjacent the lower end thereof, entrance to the interior of classifier 34 from chamber 39 being provided through the ring of openings 40. As shown in Figure 6, openings 40 may be fully or partially closed by a sliding door 41 in the form of a ring. The vertical adjustment height of door 41 is controlled around the periphery of chamber 39 bya series of rods 42 extending through the top of chamber 39 and having an adjustment nut 43 in engagement with the upper threaded endof the rods 42. A jamming stud 44 is provided on a bracket 45 so that'in whatever position each rod 42 is adjusted by nut 43, stud 44 which is in threaded engagement with bracket 45 can be jammed against the end of rod 42 to lock it in the adjusted position of ring 41, between full open and full closed position relative to the openings 40, as desired. Strip air at suitable pressure is admitted to chamber 39 and thence to primary classifier 34 whenever openings 40 are partially or fully opened, such strip air being supplied to inlet 46 of the ring 39. Preferably, the

openings 40 are below the discharge openings 33 from the risers 31.

A shaft. 47 extends throughout the height of tower 35 and is suitably journaled in a journal 48 at the bottom of tower 35 and in a thrust bearing journal 49 at the top of tower 3 5 and "throughan outlet pipe 50 for fully classified material. Shaft 47 in turn is keyed to a vane distributor 51 generally opposite the openings 33 from riser pipes 31. As shown, vane distributor 51 comprises a top plate bot-tommdst edgesofadjoining vanes 53. As material is;

sues from the riser pipes 3 1, heavier portions particular- Patented Oct. 20, 1959 in'carrying suitable end product particles away into a secondary classifier 54 in tower 35'above primary classifier 34.

p In exfoliating. and/or grinding a material like mica, in my new system, rock and grit material may be in the raw material fed into hopper 22 and will be separated from mica particles for removal from the system. Further, such removal of rock and grit is without deleterious effect on either the continuity of the new operation or the cleavage of mica particle from mice. particleor the grinding of mica particles to the size desired. Thus, it will be noted that in my illustrated embodiment, bottom 55 of tower- 35 and hence of primary classifier 34 slopes to a low trough or sump 56 in which a helical removal conveyor 57 is positioned. The ends of helical conveyor 57 are suitably journaled outside the walls 38 of tower 35 and one end is fastened to a sprocket which is rotated by a variable speed'motordrive set 58 as shown in Figure 5.

Heavy reject material directed into sump 56 is carried out of the new mill by conveyor 57 into a discharge box 59 having an annular partition 60, the opening in which is confined for a distance extending toward the bottom opening 61 of box 59 by a cylindrical flange 62.'. Air is admitted into a fitting 63 between the inside of box 59 and the outside of flange 62 to create a whirling rising sweep air current which, while heavy reject material like rock and grit of relatively higher bulk density falls through the inside of flange 62 and passes out of bottom opening 61, enables lower bulk density end product material to be picked up by such sweep air and carried off and upwardly through an uptake pipe 64' which discharges into primary classifier 34. In that way, assurance against loss of desired material from the new system is obtained while at the same time the new system rids itself continuously of waste or foreign matter such'as schistwhich occurs with mica deposits.

As more particularly shown in Figure 3, the lower end 65 of each return pipe 36 discharges into entry chamber 19. The upper end of each return pipe 36 terminates at the outside of the lower end of tower 35'. An internal coaxially positioned and spaced cylindrical liner 66 projects into the bottom of primary classifier 34' in such a manner that the upper projecting edge 67 of liner 66 forms a dam above portion 68 of bottom surface 55. A sweep air inlet pipe 69 admits air into the space 70 between the outside of liner 66 and the inside of pipe 36 thereby tending to give the sweep air a whirling or tangential motion as it moves around the lower end of lining 66 and then upwardly into the bottom of primary classifier 34. Thereby, finer particles are removed from the coarser reject particles moving downwardly through lining 66 and thereby through return pipe 36 into the respective entry chambers 19. At the same time, the dam 67 permits heavy reject material to move along bottom 55 towards sump56without interfering with the flow of coarser particles through return pipe 36, Such coarser particles from return pipe 36 are propelled through the respective jets 14 and further reduced and/ or separated by impact against one another in the discharges from the respective jets 14 in impact chamber 11. The

upper end of space 70 is blanked off by the wall and 4, a gaseous stream through outlet pipe 50 and its branch 71. The remainder of the desired'portion of the raw material not sufficiently reduced in size and/ or separated is circulated or recirculated to jets 14 via return pipes 36 and downcomer pipes 37 with the aid of the cooperating elements in primary classifier 34 and in secondary classifier 54. Generally, coarser end particles will return through return pipes 36 as a consequence of rejection by vane distributor 51 and by the portions of spinner blades 72, 73 and 74 nearer shaft 47. Finer end product material still not yet suitably reduced in size and/or separated for movement through outlets 50 and 71 will be returned by spinner blade tiers 72, 73 and 74 to a bustle chamber75 communicating with the upper ends 76 of downcomer pipes 37. The lower ends 77 of downcomer pipes 37 also discharge into the respective entry chambers 19.

In secondary classifier 54, the desired end portion material rising therein in a gaseous carrier medium such as air encounters one or more of the spinner blade tiers 72', 73 and 74. Each tier is fastened to shaft 47 by a collar 78 and a plate 79'to'which the radially extending blades 72, 73and'74'ineach of the tiers are respectively imrnovably afiixed. Hence, as shaft 47 rotates in the direction of the arrow, vane distributor 51 and the spinner' blade tiers 72 to 74, inclusive, will also rotate and perform their respective classifying functions. Preferably, the radial arms or blades 74 in tier 74 are somewhat longer than the blades in tier 72. Similarly, if desired, the blades in tier 73 may be made of a length intermediate therespective lengths of the blades72 and 74, respectively. A variable speed drive motor set 80 mounted on the top of tower 35-drives pulley 81 through a belt 82, the pulley 81 being keyed to the top of shaft 47.

Preferably, the blades 72, 73 and 74 in the tiers of like number are in angle form in cross section with the horizontally placed sides respectively designated 72a, 73a and 74a, leading. Thereby, end product material somewhat less coarse'than that which would be rejected by'vane distributor 51' is encountered by inner portions of the respective blades in the respective tiers and some at least of those less coarse portions of the desired end product may be returned within tower 35 and passed downwardly through classifier 34 into the open upper ends of the lining 66 in return-pipes 36;

Finer portions of the desired endproduct material which'nevertheless are not suitable for further ascent in tower 35 tend to move outwardly along the respective blades in the respective tiers beneath the horizontal angle sides until discharged outside of the wall 138 and within bustle chamber 75. Solid particles entering chamber 75 pass into upper ends 76 of downcomer pipes 37 and thence pass into'the jets 14 for recirculation and further reduction in size and/or separation in'the nature of exfoliation in the case of mica being the end product or of fiber separation in the case of mica being the end product or of fiber separation in the case of asbestos being the desired end product.

Between the respective tiers of spiner blades, wall 38 comprises two ring sections designated 38a and 38b respectively aflixed to the wall of chamber 75 by spacer lugs 83. A collector ring 84 having an endless undulating character closes-the space between wall 38 and the vertical wall of' chamber 75 below tier 72. The lowermost portions of collector ring 84 'form respective troughs 85 which coincide with the bottom of the opening into upper ends 76 of downcomers 37. Hence, finer reject desired end product material passing downwardly through chamber 75 mayrencounter the top of ring 84 and thence be conducted by ring 84 toward the discharge trough portions where the finer rejected material passes into the downcomer pipes 37'.

The ascent of desired end product particles through the remaining'height' o'f tower 35 above secondary classifier 54- tends to afford a further opportunity for classification as the end product material and carrier gas spiral toward the outlet pipe 50. That outlet pipe 50 may, if

desired, provide a still further classification in having the lower end thereof project-downwardly a predetermined distance within tower 35; It will be noted that in my new particle mill system, I have provided means for ridding desired end product material of unwanted heavier specific gravity components. such, for example, as rock and grit. In addition, I have provided a new particlemill system which will reduce endproduct particles in size to generally any condition of-fine'ness desired. In addition, as in the case of mica and asbestos, as illustrations, I also provide means whereby mica particles are exfoliated and in the case of asbestos where asbestos fibers are separated. Throughout the operation of my new system, the circulating streams and flOWs of materials and gases are continuous. Adjustments are readily made tion in my new system. Of course, the raw material charged to my new particle system may, if desired, be composed Wholly of desired end product material without contaminants or foreign material such'as rock and grit, in which event, the heavy reject removal device including conveyor 57, will not be operated." I

Reference is made to application Serial No. 452,116, filed August 25, 1954, for United States patent for Impact Mill. I j

Various changes in details of construction and in arrangements and in raw materials and in desired end products may be made without departing from the spirit of my invention or the scope of the appended claims.

I claim:

1. In a particle mill, in combination, an impact'chamber, opposed jet circulating means discharging into said chamber, a raw material feed device discharging into; said chamber, a riser pipe connecting said chamber with a primary classifier, adjustable means for admitting strip air to said primary classifier adjacent the lower end thereof, a rotating shaft in said primary classifier, a vane distributor mounted on said shaft, a return pipe connecting the lower end of said primary classifier with said jet circulating means, a heavy reject removal device positioned in the bottom of said primary'classifier, meansfor introducing countcrcurrent sweep air into said return pipe, an uptake pipe connected to said removal device and discharging into said primary classifier, a secondary classifier in superposed relation to said primary classifier, a rotating shaft in said secondary classifier, a plurality of radially extending blades in said secondary classifier, said blades having an angle with a generally horizontal flange of said angle leading, the ends of said blades further projecting through the wall of said secondary classifier, a bustle chamber surrounding said secondary classifier and the outer ends of said blades, a downcomer pipe connected between said bustle chamber and said jet circureach of said conveyor-to enable said heavy material to. be removed from said mill, means for returning oversize end product material from said primary classifier to said jets, a secondary classifier connected to said primary classifier to receive gas-borne end product material from said primary classifier, spinning means in said secondary classifier to reject coarser and heavier end product material, means for returning said coarser and heavier end product material from said secondary classifier to saidjets,r means for feeding raw material to said mill, and an outlet for gas borne end; product material not rejected in said secondary classifier.

3. In a particle mill, in combination, an impact chamber, opposed jets having discharge ends directed into said chamber, a feed device for raw material including desired lighter material and undesired heavier material, means for discharging the contents of said chamber into a primary classifier through the side thereof, means for admitting strip air to said classifier adjacent said first .mentioned means, vertically extending horizontally rotatable vanes positioned centrally in said classifier and opposite to said first-mentioned means, means above and below said vanes for returning overweight lighter particles from said classifier to said jets, a removal device for said heavier material positioned adjacent the bottom of said classifier, and an outlet in said classifier for lighter material meeting classification requirements.

4. In a particle mill, in combination, an impact chamber, jet circulating means discharging into said chamber, a classifier connected by external pipe means to said jet circulating means, means for admitting strip air to said classifier, a horizontally rotating shaft in said classifier, a vertically extending vane distributor mounted on said shaft, said pipe means communicating with the interior of said classifier through the side thereof adjacent to said vane distributor, fluid-borne passage means above and below said distributor for returning heavier particles from said classifier to said jet circulating means, a heavier material removal device positioned in the lower" portion of said classifier, an outlet for fully classified lighter particlesin said classifier, and means for feeding solid material to said mill.

5. In a particle mill, in combination, an impact chamber, opposed grinding jets discharging into said chamber, means for supplying a gaseous'medium under pressure to said jets as a carrier for particles in said mill, a riser pipe for the discharge of material and gas from said chamber, a classifier connected to said riserpipe, a horizontally rotatable vertically extending vane distributor mounted in said 'classifieradjacent the connection between said classifier and the riser pipe, a return pipe connected with the lower portionof said classifier and the inlet end of said jets to recirculate particles rejected in said classifier, a removal conveyor positioned in the lower portion of said classifier to remove heavier material from said mill, and a dam connected to said return pipe and projecting into -said classifiertoshield said return pipe against receipt of said heavier material.

6. In a particle mill, in combination, an impact chamber, opposed jet means discharging into said chamber, means for supplying a gaseous medium under pressure to said jet means as a carrier for particles in said mill, a riser pipe for the discharge of the contents from said chamber, a classifier connected at its side to said riser pipe, a rotatable distributor mounted in said classifier opposite to the connection between said classifier and riser pipe, said distributor having vertically extending distributing means positioned centrally in said primary radial vanes and a plate closing the sectors between said vanes adjacent the upper end of said distributor, a return pipe connecting the lower portion of said classifier with the inlet end of said jet means to recirculate particles rejected in said classifier, and means for introducing sweep air into said return pipe in a generally tangential and counterflow direction to the flow of gas and rejected 7 particles passing through, said return pipeto said'jet means.

7. In a particle mill, in combination, an impact chamber, jet circulating means discharging into said chamber, a classifier, a riser pipe connecting said chamber to a classifier, means in said classifier for separating heavier end product particles from lighter end product particles, means for returning said heavier end product particles to said jet circulating means, a bottom in said classifier sloping to a sump portion thereof, a removal conveyor extending along said sump portion to remove material heavier than said end product particles, a discharge box into which. said removal conveyor discharges such heavy material, and means for circulating countercurrent sweep air through said heavy material outside of said classifier to return to said mill whatever end product particles may be in said heavy material.

8. In a particle mill system, in combination, the steps comprising, jetting material into collision impact in an impact zone, feeding raw material directly into said impact zone, delivering the contents of said zone including said raw material into a classifier in a fluid stream, dispersing at least heavier components of said first-named stream in said classifier by striking such heavier components, withdrawing relatively lighter end product particles from said classifier in a fluid stream, returning respectively heavier end product particles to said jetting step in a fluid stream, and mechanically removing from said system said heavier components.

9. In a particle mill system, the steps comprising, in combination, forcing material to collide in an impact zone, discharging the contents of said zone into a classifier zone through the side thereof, mechanically striking at least the heavier portions of said contents in said classifier zone, introducing stripping fluid into said classifier zone below the level of entry of said contents into said classifier zone, removing heavier portions of said contents from the bottom of said classifier zone, subjecting said heavier portions to a countercurrent flow of fluid adj acent said classifier zone to provide additional separation, intersecting material rising in said classifier zoneand spinning heavier portions of said rising material to the outside of said classifier zone, removing said heavier portions of said rising material, and removing still rising material from said classifier zone.

10. In a particle mill, in combination, an impact chamber, opposed jet circulating means discharging into said chamber, a raw material feed device discharging into said chamber, a riser pipe connecting said chamber with the side wall of a primary classifier, adjustable means for admitting strip air to said primary classifier adjacent, the lower end thereof, a rotating shaft in said primary classifier, a vane distributor mounted on said shaft opposite to said riser pipe connection, areturn pipe connecting the lower end of said primary classifier with said jet circulating means, a secondary classifier in superposed relation to said primary classifier, a rotating shaft in said 0. secondary classifier, a plurality of radially extending blades in said secondary classifier, the ends of said blades further projecting through a wall member in said secondary classifier, a surrounding chamber in said secondary classifier into which the outer ends of said blades extend, adowncomer pipe connected between said lastnamed chamber and said jet circulating means, and an outlet for fully classified end product material positioned generally above said secondary classifier.

11. In a particle mill classifier, apparatus comprising, in combination, a classifier vessel, a primary classifier portion adjacent the lower end thereof, means for introducing material to be classified through the side of said classifier, a rotating shaft positioned axially in said primary classifier portion, a vertically extending distributor with radially extending vanes mounted on said shaft adjacent said first-named means, an outlet means connected to the lower end of said primary classifier portion to remove heavier portions of said material from said primary classifier portion, means for introducing strip air around the lower end of said primary classifier portion adjacent and above said outlet means, a secondary classifier portion in the upper portion of said classifier vessel, a rotating vertical shaft positioned axially in said secondary classifier portion, a plurality of superposed sets of spinner blades in said secondary classifier portion mounted on said last-named shaft and extending radially outwardly therefrom, the ends of said spinner means projecting through a wall portion of said secondary classifier portion, a chamber surrounding said last-named wall portion, an outlet means connected to said lastnamed chamber to remove heavier portions of material in said secondary classifier portion, an outlet for relatively lighter classified material positioned generally above said spinning means, and means including a variable speed prime mover to regulate fluid stream flows through respective portions of said classifier vessel.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES The Majac Pulverizer, Majac Engineering Company, Blawnox, Pennsylvania (large single sheet doubly folded, both sides cited).

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent N00 2,909,331 October 20, 1959 George M, Croft It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 49, for "138" read 38 lines 55 and 56, etrike' out "in the case of mice. being the end product or of fiber separation",

Signed and sealed this 22nd day of March 1960.

(SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

